I have a 2005 roadster limited that recently started hesitating or stalling during acceleration. I did search the forum for similar issues, Nada. I do have a code logged in the computer. It's P0453 stands for “Evaporative Emission System Pressure Sensor/Switch High. However I have had that code for sometime.

I don't have any fault codes related to ignition, fuel, or air. I have no idea of what to start looking. Typically I would wait for an engine code and then start trouble shooting from there.

 

I don't want to send you on a wild goose chase, but someone on the fakebook page had a similar problem. It was the throttle sensor/pedal.
I don't know if that's what is causing your trouble. Have your tried the Throttle Reset procedure?
1. Turn the ignition key to the on (not start) position.
2. Press the gas pedal to the floor and hold for five seconds.
3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.
4. Wait at least two minutes for ECU to reset.
(you might have to do this more than once).

 

That code could be causing the symptoms you describe. Doing a throttle reset is a good idea. However, if it were me I would clear the code, both active and stored, and see if it returns. It may take some driving for the car to throw the code again as the EVAP system is only tested after a few driving cycles have taken place. If the code returns you have found your problem. The cars are 20 years old now and the EVAP system has started to come up more often on the forum.

 

The fact that you have no misfire, O2 or other codes makes me think it's either the sensor in the accelerator pedal or the mechanism in the throttle body. The fact the ECU does not see a problem indicates to me that the pedal sensor is simply not telling the ECU the truth about pedal position or movement.

I"d lean toward the pedal first, myself. Changing it means changing the entire pedal/sensor assembly and its not cheap - but it IS easy to do.

IF that does not do it, I'd change the throttle body.

I am not convinced the evap system can do this, I've had P0453, back when the ground pin of the sensor connector got all corroded because I (oops) washed the car with the top down and was not as careful as I thought it was. THe car ran fine. (This was on my first 2005 Roadster, years ago.....)

 

Thanks all for the answers. For some reason, I only got one notice for the multiple replies that were posted. I have not gotten back to the car to test possibilities. With the rain coming up this weekend, testing might be further delayed. Sigh!

Based on the information above, I have a plan.
1) Clear any codes.
2) Reset the pedal position, easy to do and does no harm.
3) Pull the throttle body and clean the heck out of it. Gunk might be interfering with the flap. After inspection, I will be able see the condition on the TB. I will see if my scanner has a TB test movement test.
4) Test Drive with scanner.
5) See what happens and then make a decision on where to go based on cost.

One thing I did not mention and after reading the replies, I think might be related. At stop lights at idle the car does this brief drop in RPMs. Early when I got the car, this would happen more often. After driving it a while, the problem did seem to clear up. Recently it started coming back. So I am leaning towards the TB as my foot is on the brake and the pedal sensor should be sending the min position value. I did see a post that the TB sensor can be cleaned. See below.

New Bosch TB are ranging between 300 and 400 new. (Mercedes Throttle Body - Bosch 1131410125) This is a part I would buy new and not trust junk yard pulls.
The acceleration pedal position sensor seems to be built into the pedal and not a separate part. That part is about 375 to 450. Not cheap at all.

Reference Cross Posts:
https://www.crossfireforum.org/forum...on-sensor.html

 

Try needswings.com for the throttle pedal, better price and Rob sells quality parts.

 

Excellent Advice on Needswings: https://needswings.com/throttle-body-upgrade-m112

I took my cover off and I had a heck of time trying to find the TB. My first impressions was I could not see it.


Somewhere there is a throttlebody

I took a look in the manual about the removal procedure and found this:

TB removal, not using penicillin


And I found the troubleshooting chart for my issue.


I am going to go ahead and remove the TB so I can at least clean it. I did do the accelerator pedal reset and that did not fix anything.

 

That is how the current forum software works. You get one notice and no more notices until you visit the site - that resets the "new posts" flag.

That idle speed variation thing is kinda common. My car runs fine but does that a few times a year.
If it does it very often, it's a clue, if it does it once every 50 trips - not really a clue.

 

Watch the video below.CAUTION: When you take off the MAF sensor locking ring be careful. The plastic is brittle and may break. Luckily the parts are still available. (Ask me how I know )

 

Thank you for the video, that was very very helpful.
I removed the MAF, bendy tube, and TB. The MAF and bendy tube were not too bad. Hardly any dirt came off. However the TB and slum city and the intake was horrible.

Dirty Dirty

I cleaned the TB and intake put everything together and tested the car. It's much better but as I was pulling in my driveway I felt a hesitation. According the diagnostic chart, it's spark plugs next.

The car is at 126K miles. From the reading I have done on the forum, I strongly suspect that spark plugs and wires should be replaced. With the amount of work in that replacement job, I think replacing the valve cover seals should be done as well. Going to get the spark plugs from needswings. Are the magnacore wires worth it?

 

Do the plugs with the valve covers off. It is much easier. Needswings has tools to help with the plugs.

 

Needswings sells an oil catch can. It will help keep the junk from getting to the throttle body and intake.
At your mileage i would consider changing the coils right along with the plugs and wires. Look at the back of your coils; some may already have cracks. FCPeuro will have kits available that might save some money and they have the life time guarantee.
I have Magnecor on both my Crossfires, but it is mostly for dressing up the engine bay as both my cars go to local cars shows; Do they give me better performance. I do not notice a difference, but I haven't actually tested it either. Magnecor has given me very good personal service over the past decade and though there plug wires are guaranteed for life will buy from them again should I want another set for another car. The Magnecor are more difficult to remove and install as the boots are rubber or silicone. The steel surrounds on the OEM plug wires make it much easier to remove using the special 15mm wrench.

Have you checked for codes since cleaning the intake? Remember you have to have several drive cycles before some codes will set.

 

I found this kit at FCP Euro. The price is comparable to needswings. I know partsgeeks has a kit for a much lower price.
https://www.fcpeuro.com/products/mer...caAhvCEALw_wcB

I have not driven the car enough to get any codes. I will have to do so to keep the battery charged, I need to replace the alarm as it's sucking the battery down.

It seems like that my next big project will be this: Replace ignition system (new wires, plugs, and coils), install the oil catch can, and reseal the valve covers.
Thanks for all the advice. It has helped.

 

@xintersecty If you search my thread " My Journey with my 2006 Roadster "Svengoolie" " I've done everything you have mentioned. I have tons of pictures with descriptions that may be helpful.
Here's a link to a good starting point: Replacing spark plugs, valve cover gaskets, sealing breathers & more

There's a lot more in that thread as well.
Good luck,
John

 

Long time since I last posted. Finally got a break from my other flying motor issue and now I can work on the crossfire. I have been driving the car to see if I can generate a diagnostic code. Alas, plenty of times it hesitated, but no code. So I plan to replace the spark plugs, wires, and coil overs. Since the valve covers are leaking, it's time to replace the gaskets. My valve covers look terrible, I might as well get them powder coated.

I got the valve covers pulled. While pulling the covers I tore a couple of the breather hoses.

Rear breather

forward breather

I guess I need to replace those. I did some research on the oil catch can, I will make sense to install that as well when I replace the hoses.

Here is current state of the valves. I think this pretty normal for 125K miles.

Passenger side

driver side

 

With the broken hoses, I needed some replacements. Will this cover the brittle hoses when I put everything back together?

shopping list

 

Some of them.

 

So long as the plastic "T" on top of your throttle body is okay you do not need #2. The hoses from the oil catch can connect to the car where the hoses of #2 connect on the valve covers. The suction line from the oil catch can connects to the plastic "T" fitting on top of the throttle body and the other side of the "T" is capped off. The catch can comes with the hoses you need. You do need # 3 hose.

 

I would go to Parts Geek and order the set of 2003 Mercedese SLK320 valve cover breather hoses. I'm sure they are all hard as a rock.

 

He doesn't need the breather hoses if He buys the Needswings oil catch can. Needswings comes as a kit with hoses and clamps included. Only the larger hose from the drivers side to the MAF will be needed and that can be had at any auto parts store; Just buy the correct size hose and it will make the bend easy enough.